Percutaneous access for neuromodulation procedures

ABSTRACT

A neuromodulation system, comprises an implantable electrode which is implanted within a body adjacent to a target nerve structure to which electric energy is to be applied via the electrode and a connection port which is implanted in the body with a proximal surface thereof substantially flush with an outer surface of a skin of the body, the connection port including a device interface for electrically connecting to an external device which remains external to the body in combination with an electric line extending from the device interface to the electrode for carrying electric energy from the external device to the electrode and a cover selectively closing an opening of the external surface of the implanted connection port.

BACKGROUND INFORMATION

Many debilitating medical conditions may be alleviated by stimulatingtargeted nerves and muscles. For example, electric current may beapplied to a nerve or bundle of nerves to disrupt signals carried by, orto affect muscles controlled by, those nerves. Common examples of neuralstimulation devices include cardiac pacemakers, devices to controlepilepsy and chronic pain, etc.

In conventional applications, the ability of neuromodulation systems tooperate over extended periods of time is limited by the endurance oftheir power supplies (e.g., batteries). This approach works well fordevices used for short time periods, but can be problematic for deviceswhich must operate beyond the life span of the batteries. For suchdevices, additional surgery may be necessary to replace the wornbatteries. Alternatively, an external power supply carried by thepatient may be connected to the implanted device by wires or otherconnections to provide a long lasting, constant power supply. However,the wires penetrating the skin increase the likelihood of infection andother negative reactions at the location where the connections penetratethe skin.

The size of components of conventional implanted neuromodulation systemsoften causes discomfort and may reduce a patient's ability to carry outroutine tasks. In addition, the cost of such implanted devices (e.g.,implanted pulse generators) may be significant. Implanted pulsegenerators also have a limited life span, usually around 5 to 10 years,after which they must be replaced. As with batteries, this may involveadditional surgery with the associated discomfort and costs. It may alsobe extremely difficult to perform upgrades or repairs to conventional,implanted pulse generators due to the same concerns described above.

SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to a neuromodulationsystem, comprising an implantable electrode which is implanted within abody adjacent to a target nerve structure to which electric energy is tobe applied via the electrode and a connection port which is implanted inthe body with a proximal surface thereof substantially flush with anouter surface of a skin of the body, the connection port including adevice interface for electrically connecting to an external device whichremains external to the body in combination with an electric lineextending from the device interface to the electrode for carryingelectric energy from the external device to the electrode and a coverselectively closing an opening of the external surface of the implantedconnection port.

In a further aspect, the present invention is directed to a method forneuromodulation therapy, comprising surgically implanting an electrodeadjacent to a target nerve structure and implanting a connection portincluding a housing which, when implanted, lies beneath a surface of theskin, the housing defining an opening to a surgically created opening inthe skin, the connection port including a device interface forelectrically coupling to an external device and a cover selectivelysealing the opening in combination with forming a tunnel between theincision site and the implanted connection port and passing an electricline though the tunnel to connect the device interface and theelectrode. A connector of an external medical device is inserted throughthe opening and coupled to the device interface electric current isapplied from the external device to the electrode via the deviceinterface and the electric line.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a diagram of a neuromodulation system with external pulsegenerator according to an embodiment of the present invention;

FIG. 2 shows a diagram of a passive valve used in a connector for aneuromodulation system according to the present invention; and

FIG. 3 shows a diagram of another passive valve used in a connector fora neuromodulation system according to the present invention.

DETAILED DESCRIPTION

The present invention may be further understood with reference to thefollowing description and the appended drawings, wherein like elementsare referred to with the same reference numerals. The present inventionrelates to devices used to block nerve signals and to stimulate selectednerves. In particular, the present invention relates to nervestimulation devices comprising a first implanted portion and a secondexternal portion connected to the implanted portion through an implantedconnection port.

As described above, a variety of medical disorders are now treated vianeuromodulation (i.e., the application of electrical stimuli to atargeted nerve or bundle of nerves). The stimulation may be designed tointerfere with the electrical activity of the target nerves by blockingit, or by applying different electrical signals to the nerve(s). Aswould be understood by those skilled in the art, such procedures may beemployed to treat a variety of ailments including, for example, movementdisorders such as Parkinson's disease and Multiple Sclerosis, epilepsy,chronic pain, stroke, Alzheimer's disease, head injuries, spinal chordinjuries, Hydrocephalus, obesity, urinary urge incontinence, fecalincontinence, interstitial cystitis, chronic pelvic pain andpsychological disorders such as depression. Depending on the conditionbeing treated, different stimuli may be applied to the target nerve(s).However, in general, the hardware components used are substantiallysimilar.

The treatment of urinary urge incontinence, for example, often involvesthe implantation of a bulky and expensive Pulse Generator (IPG). The IPGgenerates electrical pulses the intensity and duration of which aretailored to supply desired signals to the nerves connected to specificmuscles. IPG's have a finite life of about 5 to 10 years after whichthey must be replaced through invasive surgery. One example of an IPGfor treating urinary urge incontinence is the Interstim device,available from the Medtronic Corporation.

To reduce the costs of neuromodulation treatment, a system according tothe present invention utilizes external components in place of severalof the implanted components of prior systems. This approach reducespatient discomfort and eliminates additional surgery for replacing orupdating most of the system components. In these systems, a lead andelectrodes are implanted with the electrodes in contact with, or inproximity to, the target nerve(s). A connection port is implanted at aconvenient location (e.g., in proximity to the lead or a selecteddistance therefrom with an extension connecting the lead to theimplanted connection port). The bulkier and more expensive components ofthese systems (e.g., the pulse generator) remain external and areconnected to the implanted components via the implanted connection port.

The embodiments of the present invention describe a neuromodulationsystem utilizing an implanted connection port to facilitateneuromodulation and/or neurostimulation procedures, eliminating the needfor an IPG (or other large device) by allowing connection between theelectrodes and external devices via the implanted port. The port may beplaced substantially even with a level of the skin and may include ahousing which extends a small distance below the skin level. The port isconnected to a lead with electrodes which interface with a targetednerve structure (e.g., a nerve, nerve bundle or nerve junction) to allowexternal devices to be connected to the electrode leads for theapplication of various therapeutic signals (e.g., test stimulationsignals and/or predetermined neuromodulation signals) to the targetnerve structure. The external devices which can be connected to theimplanted connection port include, but are not limited to, TestStimulators, Programmers and Pulse Generators. These devices may be handheld, table top mounted, or may be wearable by the patient to enhancepatient mobility.

Using a connection port at the skin level to couple one or more externalcomponents (e.g., a pulse generator) to electrodes greatly reduces thecost of the implant. Both the implantation and subsequent care andmaintenance of the system are simplified decreasing discomfort andreducing the risks and costs associated with surgery. The system alsoincreases flexibility in selecting treatment options, and frees thepatient to select between a larger number of physical locations at whichthe treatment may be performed. The connection port according to theinvention allows the connection of a table top pulse generator located,for example, at a physician's office, a hospital, or in the patient'shome. Hand held devices or other portable devices may then be employedat any time and/or place desired by the patient or physician. Inaddition, a patient wearable external device may be placed on a belt, awristband or carried in a pocket.

FIG. 1 shows an exemplary embodiment of a neuromodulation system 100according to the invention, which includes an implantable connectionport 102. The system 100 is designed to stimulate a target nervestructure 122 with electrical impulses. According to embodiments of theinvention, the implanted connection port 102 is used to connect one ormore external components of the system 100, for example a pulsegenerator or programmer 116, to an implanted extension 112 coupled to alead 113 extending to electrodes 114 which are coupled to a distal endthereof. In many cases, the electrodes 114 will be positioned adjacentto the target nerve structure 122 with the lead 113 extending therefromto a proximal end connected to the implanted connection port 102 eitherdirectly or via the extension 112. In many cases, the distance betweenthe implanted connection port 102 and the electrodes 114 will beminimized. However, when longer distances are necessary to simplify thesurgical procedure and/or to enhance patient comfort, an extension 112with an extension connector 110 may be coupled to the proximal end ofthe lead 113 to span the distance between the implanted connection port102 and the target nerve structure 122, as shown in FIG. 1.

According to the exemplary embodiment shown in FIG. 1, the implantedconnection port 102 comprises a housing 104 that is placed below theskin layer 120. A connection jack 108 is mounted within the housing 104connected to the extension cable 112 that extends out of the housing 104to the extension connector 110 which is connected to the lead 113 andthe electrodes 114. The lead 113, the electrodes 114, the extensioncable 112 and the connector 110 are positioned by tunneling to theelectrode implant site and feeding the electrodes 114, the lead 113, theconnector 110 and the extension cable 112 through the surgical tunneluntil the electrodes 114 reach the electrode implant site while theproximal end of the extension cable 112 extends to the connection jack108 in the implanted connection port 102. Those skilled in the art willunderstand that the extension cable 112 may be provided in differentlengths to accommodate different distances between the site of the port102 and the electrode implant site and that the extension cable may beconnected directly to the lead 113 without the extension connector 110.During assembly of the implanted connection port 102, the extensioncable 112 may be passed through an opening 109 of the housing 104, andconnected to the connection jack 108 which may then be sealingly fixedto the housing 104. FIG. 1 shows one pair of electrodes. it isunderstood that multiple pairs can be employed to increase thelikelihood of stimulating the correct site, or to selectively activateelectrodes to maximize treatment on an ongoing basis (for example iflead migration occurs).

According to the exemplary embodiment of the invention, the housing 104of the implanted connection port 102 comprises a passive elastomericvalve 126 covering an external portion of the housing 104. Morespecifically, the housing 104 comprises a cover 106 which covers anentire outward facing opening of the housing 102. The cover 106preferably includes the passive elastomeric valve 126 over a portionthereof. In one embodiment, the passive elastomeric valve 126 comprisesa disk made from an elastomer, such as silicon, C-Flex, latex, etc.,with one or more slits cut thereinto. These slits are biased to a closedposition by the elastomeric material. However, as would be understood bythose skilled in the art, these slits may be easily opened by pushing anelectrical connector or other component therethrough to enter thehousing 102 and connect to the connection jack 108. The cover 106 andthe passive valve 126 prevent contaminants such as dirt, fluids,bacteria etc. from entering the housing 104. At the same time, thepassive valve 126 facilitates insertion of an electrical lead, such as aconnector 118 of a pulse generator 116, into the housing 104, so that itmay be mated to the connection jack 108. The connection jack 108 may,for example, be a standard phone jack configured to receive anelectrical connector such as a shrouded multi-conductor phone connector.However, those skilled in the art will understand that any of a varietyof known or custom connection jacks may be used for the connection jack108 so long as it is configured to receive the connector of thedevice(s) which are to be connected to the electrodes 114. Those skilledin the art will understand that the slits may take on any of a varietyof shapes extending along portions of one or more curves, tricuspidshapes, etc.

FIG. 2 shows an exemplary embodiment of a cover 206 with a passiveelastomeric valve 208, according to the invention. The valve 208 isformed of a thin (0.005″-0.100″) elastomeric membrane 212 with a slit210 cut therethrough. The dimensions of the membrane 212 and of the slit210 may be adjusted to obtain the desired closing force which retainsthe valve normally closed, and may vary depending on the materialforming the valve 208. FIG. 3 shows an alternative exemplary embodimentof a cover 306 according to the invention. Here, the cover 306 has apassive elastomeric valve 308 formed of a membrane 312 with a pair ofslits 310 arranged in a cruciform pattern. The slits 310 preferably havea size and shape optimized for insertion of an electrical contacttherethrough with a natural shape of the membrane 308 urging the and toretain the valve 308 closed in normal operation, when the electricalcontact is removed.

In a different embodiment according to the invention, the cover 106, 206and 306 of the housing 104 may be replaced by a simple removable cap. Inthis manner, the additional expense of manufacturing a passive valve iseliminated. For example, the removable cap may be removed to permitinsertion of the connector 118 into the housing 104. When the connector118 is not in use, the housing 104 is closed by replacing the cap. In adifferent exemplary embodiment, the connector 112 and the connector jack108 are formed integrally with the housing 104. In this case, theimplanted connection port 102 may preferably be provided with extensioncables 112 of different lengths to suit a variety of applications. Inaddition, the extension cables 112 and other component of the system 100may preferably be coated with an antimicrobial compound, to preventinfection.

During an exemplary procedure for implanting a neurostimulation systemaccording to the present invention, an incision is made and theelectrodes 114 are placed adjacent to the target nerve structure 122. Atunnel is then surgically formed between the site at which theelectrodes 114 are implanted and the site at which the implantedconnection port 102 is to be placed with the lead 113 extending into thetunnel toward the site of at which the connection port 102 is to beimplanted. In some cases, these two locations are substantially thesame, and tunneling is not necessary. A temporary sheath may be leftbehind in the tunnel site, so that the extension cable 112 can later befed through the sheath to be joined to the proximal end of the lead 113.As would be understood by those skilled in the art, the extension cable112 may be made available in different lengths to accommodate differenttunneling distances. After the extension cable 112 has been positioned,the sheath is removed over the cable, and the extension cable 112 ismated to the lead 113 via the extension connector 110. The incision atthe site of the implantation of the electrodes 114 may then be closedand the implanted connection port 102 is fixed to the skin usingconventional methods as would be understood by those skilled in the art.

A test stimulation of the target nerve structure 122 may then beperformed to verify the appropriate response prior to finalimplantation. After the surgical aspects of the procedure have beencompleted, the implanted connection port 102 is used to connect externalcomponents to the electrodes 114 via the lead 113. For example, theconnector 118 of a pulse generator 116 may be inserted into the housing104 through the passive elastomeric valve 126 and connected to theconnection jack 108. As would be understood by those skilled in the art,various therapeutical stimuli may then be delivered directly to thetarget nerve structure 122 based on, for example, a schedule selected bymedical personnel programmed into the pulse generator 116.

The present invention has been described with reference to specificexemplary embodiments. Those skilled in the art will understand thatchanges may be made in details, particularly in matters of shape, size,material and arrangement of parts. Accordingly, various modificationsand changes may be made to the embodiments. For example, the location ofthe implanted components of the system may be varied to reflect thelocation of the nerves and muscles that are to be stimulated. Additionalor fewer components may be located external to the body of the patient,depending on the condition that is being treated using theneurostimulation system. The specifications and drawings are, therefore,to be regarded in an illustrative rather than a restrictive sense.

1. A neuromodulation system, comprising: an implantable electrode which,when in an operative position, is implanted within a body adjacent to atarget nerve structure to which electric energy is to be applied via theelectrode; a connection port which, in the operative position, isimplanted in the body with a proximal surface thereof substantiallyflush with an outer surface of a skin of the body, the connection portincluding a device interface for electrically connecting to an externaldevice which remains external to the body; an electric line extendingfrom the device interface to the electrode for carrying electric energyfrom the external device to the electrode; and a cover selectivelyclosing an opening of the external surface of the implanted connectionport.
 2. The neuromodulation system according to claim 1, wherein thecover is removable from the external surface of the implanted connectionport to expose the device interface.
 3. The neuromodulation systemaccording to claim 1, wherein the electric line includes an extensionconnector extending from the device interface to a lead connected to theelectrode.
 4. The neuromodulation system according to claim 1,whereinthe cover comprises a passive valve
 5. The neuromodulation systemaccording to claim 4, wherein the passive valve includes an elastomericmembrane having a slit formed therein.
 6. The neuromodulation systemaccording to claim 5, wherein the elastomeric membrane is one of asilicon membrane, a C-Flex membrane and a latex membrane.
 7. Theneuromodulation system according to claim 5, wherein the elastomericmembrane comprises one of a linear slit, a cross-shaped slit and atricuspid slit.
 8. The neuromodulation system according to claim 5,wherein the passive valve is biased toward a closed configuration and isopenable by inserting an electrical connector therethrough.
 9. Theneuromodulation system according to claim 1, wherein the external devicecomprises one of a pulse generator, a test stimulator and a programmer.10. The neuromodulation system according to claim 9, wherein aneuromodulation signal generated by the external device is selected totreat one of Parkinson's disease, Multiple Sclerosis, epilepsy, chronicpain, stroke, Alzheimer's disease, head injuries, spinal chord injuries,migraine headaches, Hydrocephalus, obesity, urinary urge incontinence,fecal incontinence, interstitial cystitis, chronic pelvic pain anddepression.
 11. The neuromodulation system according to claim 1, whereinthe connection port includes a housing which, when in the operativeposition, is disposed substantially subcutaneously below the cover, thedevice interface being mounted within the housing with the electric lineextending through a wall of the housing into the body.
 12. Animplantable connection port for coupling an external device to asurgically implanted electrode, comprising: a housing defining aninterface chamber therewithin and a proximal opening which, when thehousing is in an operative position, faces an outer surface of a skin ofa body within which the connection port is implanted; a cover extendingacross an opening in the housing wherein, when in an operative position,the cover lies substantially flush with the outer surface of the skinwith the housing extending beneath the cover within the body, the coverbeing selectively openable to receive an electrical connector of anexternal device through the opening in the housing; and a connectionjack mounted within the housing for coupling to an electrical connectorof the external device.
 13. The connection port according to claim 12,wherein the cover includes a passive valve biased toward a closedposition, the valve being openable to receive the electrical connectortherethrough
 14. The connection port according to claim 13, wherein thepassive valve includes a slitted elastomeric membrane.
 15. Theconnection port according to claim 12, wherein the cover comprises aremovable cap.
 16. The connection port according to claim 12 wherein thecover comprises a hinged cap.
 17. The connection port according to claim12, further comprising an extension cable extending from the connectionjack through a wall of the housing for connection to an implantedelectrode.
 18. The connection port according to claim 12, wherein theconnection jack is integral with the housing.
 19. The connection portaccording to claim 12, wherein the housing further comprises anantimicrobial agent coating.
 20. The connection port according to claim12, wherein the housing is adapted to be sutured to the skin.
 21. Theconnection port according to claim 14, wherein the elastomeric slittedmembrane is made of one of silicon, C-Flex and latex.
 22. The connectionport according to claim 14, wherein the elastomeric slitted membranecomprises one of a linear slit, a cross-shaped slit and a tricuspidslit.
 23. The connection port according to claim 14, wherein theelastomeric slitted membrane comprises one of a linear and a cruciformslit.
 24. A implanted connection port for an external medical device,comprising: a housing which, when in an operative position, is implantedunder a skin of a body; an openable cover of the housing which, when inan operative position, is accessible from outside the body; and aconnection jack within the housing, the jack including a proximal endconnectable to a connector of an external device when the cover is openand a proximal end coupled to an electric line for connection to animplanted electrode.
 25. A method for neuromodulation therapy,comprising: surgically implanting an electrode adjacent to a targetnerve structure; implanting a connection port, the connection portincluding a housing which, when implanted, lies beneath a surface of theskin, the housing defining an opening which, when the connection port isimplanted, is open to a surgically created opening in the skin, theconnection port including a device interface for electrically couplingto an external device and a cover selectively sealing the opening;forming a tunnel between the incision site and the implanted connectionport; passing an electric line though the tunnel to connect the deviceinterface and the electrode; inserting a connector of an externalmedical device through the opening; coupling the connector to the deviceinterface; and applying electric current from the external device to theelectrode via the device interface and the electric line.
 26. The methodaccording to claim 25, further comprising disposing a sheath in thetunnel before passing the electric line therethrough and removing thesheath after the electric line is in place.
 27. The method according toclaim 25, wherein the cover includes a removable cap, the method furthercomprising removing the cap prior to inserting the connector through theopening.
 28. The method according to claim 25, wherein the coverincludes a slitted, elastomeric membrane, the slit being biased closed.29. The method according to claim 25, further comprising attaching theimplanted connection port to the skin, a portion of the port remainingabove the skin.
 30. The method according to claim 25, wherein the covercomprises a hinged cap.